A novel reactive power overexcitation regulation technology for synchronous generator, comprises measuring a stator voltage, a stator current, an active power and a reactive power of the synchronous generator; calculating the allowable upper limit value of the reactive power of the generator according to the allowable stator current of stator heating, and calculating the allowable value of the reactive power of the minimum stator current of the generator according to the contact reactance between the generator and the grid; comparing the stator current with its allowable value, calculate the excess calorific value of the stator of the generator if the calculated actual stator current is larger than its allowable value, enter reactive power overexcitation limiting regulation mode if the excess calorific value of the generator reaches the upper limit of the allowable heating margin of the generator; and using the larger value between the allowable upper limit value of the reactive power and the allowable value of the reactive power as the goal value of the reactive power regulation to maintain the output reactive power of the generator equal to the goal value. The present invention can protect the safety of the generator, and is beneficial to support the grid voltage to improve the stability of the power system performance.
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1. A novel reactive power overexcitation regulation technology for synchronous generator, wherein, comprising: measuring a stator voltage, a stator current, an active power and a reactive power of the synchronous generator; calculating the allowable upper limit value of the reactive power of the generator according to the allowable stator current of stator heating of the generator, and calculating the allowable value of the reactive power of the minimum stator current of the generator according to the contact reactance between the generator and the grid; comparing the calculated actual stator current with its allowable value, calculate the excess calorific value of the stator of the generator if the calculated actual stator current is larger than its allowable value, enter reactive power overexcitation limiting regulation mode if the excess calorific value of the generator reaches the upper limit of the allowable heating margin of the generator; using the larger value between the allowable upper limit value of the reactive power and the allowable value of the reactive power of the minimum stator current as the goal value of the reactive power regulation to maintain the output reactive power of the generator equal to the goal value.
2. The novel reactive power overexcitation regulation technology for synchronous generator according to claim 1 , wherein the goal value of the reactive power regulation is calculated as: { Q G 1 ( U t , P e ) = U t 2 i t lim 2 - P e 2 Q G 2 ( U t , P e ) = U t 2 2 X E U t 4 4 X E 2 - P e 2 Q G ( U t , P e ) = max { Q G 1 ( U t , P e ) , Q G 2 ( U t , P e ) } wherein, item is an allowable value of the stator current, X E is a contact reactance between the generator and the grid, P e is an active power, U t is a stator voltage, Q G1 is an allowable upper limit value of the reactive power calculated according to the allowable stator heating, Q G2 is an allowable value of the reactive power calculated according to the minimum stator current, and Q G is a goal value of the reactive power overexcitation regulation.
This invention relates to a reactive power overexcitation regulation system for synchronous generators, addressing the challenge of optimizing reactive power output while preventing overheating and ensuring stable grid connection. The technology calculates a target reactive power value (Q_G) based on two key constraints: thermal limits of the stator and minimum stator current requirements. The first constraint (Q_G1) is derived from the allowable stator current limit (i_tlim) and active power (P_e), ensuring the generator operates within safe thermal boundaries. The second constraint (Q_G2) is based on the generator's excitation reactance (X_E) and stator voltage (U_t), ensuring sufficient stator current for stable grid connection. The final target reactive power (Q_G) is the higher of these two values, balancing thermal safety and operational stability. This approach dynamically adjusts reactive power output to prevent overexcitation while maintaining grid compatibility. The system is particularly useful in power plants where reactive power regulation is critical for grid stability and generator longevity.
3. The novel reactive power overexcitation regulation technology for synchronous generator according to claim 2 , wherein the startup logic is calculated as: { i t 2 = P e 2 + Q t 2 U t 2 i t > i tth C t = ∫ ( i t 2 - i tn 2 ) dt C t > C a wherein, i tn is a stator current rating, i tth is a start threshold of stator heating calculation, C t is a calculated value of stator heat capacity, C a is an allowable pre-setting value of stator heating, P e is an active power, U t is a stator voltage, and I t is a stator current.
This invention relates to a reactive power overexcitation regulation technology for synchronous generators, addressing the challenge of managing excessive reactive power and thermal stress in generator stators during operation. The technology monitors and controls stator heating to prevent overheating while maintaining stable power output. The system calculates a startup logic based on real-time electrical parameters. The stator current (I_t) is compared to a rated current (I_tn) and a threshold (I_tth) to assess heating risk. A heat capacity value (C_t) is derived by integrating the difference between the squared stator current and the squared rated current over time. If C_t exceeds a predefined allowable limit (C_a), the system triggers corrective action to regulate reactive power overexcitation. The calculation incorporates active power (P_e), reactive power (Q_t), and stator voltage (U_t) to dynamically adjust excitation levels. This ensures the generator operates within safe thermal limits while efficiently delivering power. The technology is particularly useful in power systems where reactive power fluctuations could lead to stator overheating, improving reliability and longevity of synchronous generators.
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April 23, 2018
January 14, 2020
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